I personally believe that it is less that women and older people cant.... and more the fact that women tend to be less competitive so are less likely to try and get into a pro team.... but also women and the older you get.... the less time they actually have tbh. Between work, hanging out with friends (lets be fair, i know guys have friends too but generally guys play games together, whereas girls are more likely to go to the park or something), if they get married then chances are they could be working as well.... but when they get home they are working on trying to clean the house, do the dishes, cook dinner, take care of the kids if/when they have any (which during pregnancy you most likely would not be doing much training etc....) etc etc etc etc.
The older generation are generally slowing down a bit, have kids that are needing to be taken care of/that are using the computer, working usually longer hours, etc.
Average 20 year old males life? Work/college, make some ramen, turn on game, play with friends online.
Can a female or older person get into pros? ABSOLUTELY! What is it going to take? Pretty much having no life outside of league except the necessities needed to survive.